Safety device for grinding machines



Jan. 14, 1958 B. TOCCl-GUILBERT ETAL 2,819,570

SAFETY DEVICE FOR GRINDING MACHINES 2 Sheets-Sheet Filed Jan. 10, 1957 INVENTORS BE/PNE TOCCl-GU/LBERT BY HOSA /ER L. BL UM \J; 4& 2 4

Jan. 14, 1958 B. TOCCl-GUILBERT ETAL 2,819,570

SAFETYDEVICE FOR GRINDING MACHINES Filed Jan. 10 1957 2 Sheets-Sheet 2 INVENTORS BE/PNE TOCCI- GU/LBEET BY HOSA/(E/P L. BLUM SAFETY DEVICE FOR GRINDING MACHINES Application January 10, 1957, Serial No. 633,454

2 Claims. (Cl. 51-468) This invention relates to a safety shield for. grinding machines and particularly grinding machines which are completely portable and controlled against the work piece by the operators own efforts.

It is a well-known fact that grinding operations are becoming more and more important in the fabrication and finishing of a multitude of parts and equipment. Thousands of working men are using portable grinding tools every day in all parts of the country. Thus, whenever an injury occurs to an operator or to an adjacent workman, man hours are lost which are costly to the workman, to the manufacturer and to the consumer. The prevention of such losses is a matter of major importance.

Grinding discs are of various sizes, shapes and forms, but, essentially, they comprise a wheel which is made up of an abrasive bonded with a binder into the particular form and shape desired. Obviously, there are many kinds of abrasives, as well as sizes and spacings of the abrasive grains employed in the making of grinding wheels and discs. The bonds which hold the abrasives in the discs are numerous but are usually vitrified, silicate, rubber, resinoid, shellac or oxichloride substances. Each type of abrasive and each type of bond has its own particular optimum operating characteristics, and varying combinations are selected for certain purposes.

Grinding wheels are intended for high speed rotation of an order from 3,500 R. P. M. to 12,000 R. P. M. While it is customary for all wheel makers to test them for breaking speeds, and, as a factor of safety, to provide a strength from one to five times greater than that required for the recommended operating speeds, nevertheless grinding wheels shatter when subjected to an unexpected shock or when applied to the work after having been cracked, either through carelessness or an unnoticed previous shock. When such a fracture occurs at high rotational speeds, the fragments produce severe injuries and death. Each fragment becomes a cutting instrument. The fact that such grinding Wheels are easily broken is not necessarily an indication of poor quality. There must be weak wheels as well as strong ones in order to perform the multitudinous grinding operations which confront the ordinary fabricator. Also, certain wheels have specific limitations due to the nature of the bond used, i. e., resinoid, shellac and silicate bonds are attacked by alkaline solutions, such as soda, and rubber base bonds are weakened by oil. Grinding fluids must not only be chosen but guarded against contamination with these limitations in mind. An improper use of such solutions will weaken the bond to a point of ready fracture and disintegration without warning.

Accordingly, it is of the utmost importance that the operator of such grinding tools be protected against such hazards, and particularly operators of portable tools, whether electric, pneumatic or flexible-shaft driven, which are held in the hands of the operator and moved by him directly to the work and where the pressure and angle of operation is controlled by the operator, himself. Protecting shields have long been used for grinding and cutting wheels which are rigidly mounted, but due to. their excessive size and heavy construction, they could not be added to portable hand tools without adding so much weight that the operators fatigue is increased and his efficiency greatly reduced. The safety devices for portable tools presently known limit the flexibility and usefulness of the tool. Therefore, it is the object of the present invention to provide a safety device for portable hand grinding tools which will protect the operator at all times under all conditions from dangers resulting from the fracture of the grinding wheel, as well as inadvertent contact therewith, regardless of the speed of rotation, the angle or pressure of grind, the nature of the abrasive or bond and/or the many unappreciated and unknown reasons for fractures or human failure.

Further objects are to provide a construction of maximum simplicity, economy and ease of manufacture, also such further objects, advantages and capabilities as will fully appear and as are inherently possessed by the device and the invention described herein.

The invention further resides in the combination, construction and arrangement of parts illustrated in the accompanying drawings, and, while there is shown therein a preferred embodiment thereof, it is to be understood that the same is merely illustrative of the invention and that the invention is capable of modification and change and comprehends other details of construction without departing from the spirit thereof or the scope of the.

appended claims.

Referring to the drawings:

Figure 1. is a perspective view of the safety device showing the attaching arrangement in position for securing the same on the bearing housing of air motors with angled heads.

Figure 2 is a perspective view of the safety device of the present invention with the clamping members in position for attachment around the body portion of electric motor power units.

Figure 3 is a perspective, fragmentary view showing the safety device of Figure 2, as used on electrical grinding apparatus of the portable type, secured to the barrel of the motor and ready for use.

Referring now more particularly to the drawings in which like reference numerals are used thereon to indicate like parts in the several views, the shield member is indicated by the numeral 10. The shield member comprises a formed piece of sheet steel representing approximately of a flat ring. The ring segment 11 is bent at its outer perimeter to form a depending protective wall 12, having a sufficient height to accommodate, among other things, the varying thicknesses of grinding discs 15 without interference therewith or the work to which the disc is applied. The wall 12 has an inturned flange 16 which deflects fragments in the event of breakage of the grinding disc 15. The inner periphery of the ring segment 11 has a downturned flange 17 which projects perpendicularly to the face of the grinding wheel and is likewise an important safety factor. The shield 10, unlike other fixed grinding hoods and safety covers, need only represent an arc of about 120 as this is substantially the maximum which will permit full use of the grinding wheel or disc applied against the work in nearly all instances. The ring segment portion is provided with three pairs of through slots 18a, 18b and 180, the purpose and function of these pairs of slots being disclosed later herein.

The attachment of the shield member to the motor or to the portable grinding tool comprises a pair of angle brackets 20, a riser link 21, and a split ring collar composed of two identical faced units 22, the ends of which have outwardly directed flanges 23 and 24 (see Figure 1). The flanges 24 are not radial with respect to the diameter Patented Jan. 14, 19,58

of the split ring collar '22, but are elf-center sufiiciently to accommodate the width of the spacer riser 21. The spacer riser 21 is readily made from a piece of tubing which is flattened, leaving tubular passages at its marginal edges to permit the passage of through-bolts 25 and 26 therethrough. The spacer riser 21 is maintained between the vertical legsof the angles by means of the bolts and merely by tightening the nut 27, any adjusted position of the spacer riser with respect to the shield 10 can be secured. As indicatedabove, the bolt 26 passes through the flanges 24 which are spaced by the opposite marginal edges of the spacer riser 21 so that by tightening the nut 28 the position of the split ring collar 22 may be adjusted and maintained. In Figure 1 it will be observed that, the spacer riser 21 is positioned at a forward angle withrespect to the surface 11 of the shield 10, while the split ring collar 22 is in a horizontal plane, substantially parallel to the plane of the surface 11. It will be observed that the vertical axial alignment corresponding to the shaft of the motor (not shown in Figure 1) can be varied and adjusted while maintaining the split ring collar 22 in a plane substantially parallel to the plane of the surface 11, merely by adjusting the angularity of the spacer riser 21 with respect to the surface 11.

Practically all air motors for portable grinding, such as Thor and Ingersol-Rand, have a sufficient length to the shaft bearing housing to permit encirclement by the split ring members 22. The collar is tightened in position by the bolt 30 'which passes through the flanges 23 and tightening the nut 31. flanges 24, it is desirable to include an additional tubular spacer 32 which is maintained in position at all times by the bolt 33 and the nut 34.

This entire assembly is secured to the shield 10 by the bolts 35 which guide in the slots 18 and are secured in the adjusted position by the nuts 36. In Figure 1 the assembly is secured in slots 18b which locate the grinding disc for straight-on work.

With reference to Figures 2 and 3, the structure is identical except for the manner of attaching the same to the power tool. As shown in Figure 2, the split ring collar has three members, two of which are identical, being numbered 22a, and a semicircular member 22b. 7 he members 22a have the nonradial flanges 24 which are held in adjusted position on the spacer riser 21 by the bolt 26 and the tightening nut 28. At their other ends they have substantially radial outwardly directed flanges which face the outwardly directed flanges 41 of the semicircular member 22b. The members 22a and 22b encircle the barrel 42 of the motor 43 and are held in the adjusted position by tightening the nuts 44 on the bolts 45 which pass through the abutting flanges 40 and 41. As shown in Figures 2 and 3, the angle members are held in position on the shield 10 in the pair of slots 18c. This means that the shield is positioned for righthand operation, whereas if slots 18a had been used, the shield would be in position for left-hand operation.

It will be observed that regardless of whether the manner of attachment is that of Figure 1 or that shown in Because of the length of the 4 Figure 2, the adjustment is universal with respect to all types of portable power equipment. It is also universal in its adjustment as to height, as to movement of the axis of rotation so that the shield may be used to accommodate many sizes or diameters of discs and that the same may be adjusted to any angularity of grind fromthe flat grind to All of this is accomplished by protecting. theoperator from any possible damage or injury due to disintegration of the disc in use, and, at the same time, it protects the disc from accidental damage due to dropping or shock. In addition, due to the fact that there is great latitude in adjustment in height, the grinding discs may be used with or without the benefit of oscillators such as shown in Patents Nos. 2,633,008, 2,767,527, and

2,767,578. In addition, lateral adjustments may also be made by movement and adjustment of the device within the slots 18.

While only angle head motors have been mentioned, it is to be understood that the safety guard may be used on tools with straight motor shafts and on equipment employing flexible shafts, with equal facility and effect.

We claim:

1. A guard for protection from rotating solid abrasive discs and the like comprising in combination a split ring band means for attaching the guard to the power driven tool used for rotating said abrasive, a guard in the form of a ring segment having an outer peripheral wall with an inwardly turned terminal lip and an inner peripheral downwardly turned lip, slot means in said ring segment, an assembly connecting said band means and said ring segment in association with said slot means for adjustably positioning said ring segment both laterally and vertically with respect to the abrasive disc, and means for securing the cdonnecting assembly in the adjusted position for the guar 2. A guard for protection from rotating solid abrasive discs and the like comprising in combination a split ring band means for attaching the guard to the power driven tool used for rotating said abrasive, a guard in the form of a ring segment having an outer peripheral wall with an inwardly turned terminal lip and an inner peripheral downwardly turned lip, a plurality of slot means in said ring segment for the placement of the assembly on the tool to eflect a desired position of said ring segment and the abrasive disc, an assembly connecting said band means and said ring segment in association with said slot means for adjustably positioning said ring segment both laterally and vertically with respect to the abrasive disc, and means for securing the connecting assembly in the adjusted position for the guard.

References Cited in the file of this patent UNITED STATES PATENTS 1,945,031 Decker Jan. 30, 1934 2,106,033 Mall Jan. 18, 1938 2,301,264 Emery Nov. 10, 1942 2,707,854 Johnson May 10, 1955- 

